Researchers confirmed the presence in Japan of an invasive slug species native to Europe, but little is known on whether it could affect agricultural crops and ecosystems in the country.
The slug, Arion subfuscus, was found in Hokkaido. It reaches a length of 5 to 6 centimeters and its body color ranges from brown to yellow, depending on the individual.
It has no Japanese scientific name yet.
The research team at Toyo Institute of Food Technology based in Kawanishi, Hyogo Prefecture, published its findings in Biological Invasions, an international journal focusing on alien species, at (https://link.springer.com/article/10.1007/s10530-026-03753-2).
Tomoyasu Yamazaki, a researcher at the institute, discovered several dozen unfamiliar slugs at the Maruyama Koen park in Sapporo in 2024.
When he studied their shapes and genes at the institute, he found they were an alien slug never before recorded in Japan.
The following year, the team found the slug at five locations in Sapporo and Otaru.
The researchers said it is highly likely that they were carried into Hokkaido via cargo or other shipments.
A detailed analysis of their DNA showed that they came to Japan from Europe via the United States.
In Europe, the slugs have reportedly caused damage to vegetables, garden seedlings and other botanical materials.
As for why the slug was found in Hokkaido, Yamazaki said, “I think that is because Hokkaido’s cold climate is similar to that of Europe.”
But he warned, “From now, it is possible that it will spread to the main island of Honshu and elsewhere across the country through distribution networks or other channels.”
AloJapan.com